Searching For Dark Matter Subhalos In the Fermi-LAT Second Source Catalog

TL;DR

This study searches for dark matter subhalos in the Fermi-LAT catalog by analyzing unidentified gamma-ray sources, finding some consistent with light dark matter particles and suggesting further multi-wavelength observations.

Contribution

It identifies candidate dark matter subhalos among unassociated gamma-ray sources and compares their spectra with dark matter models, providing new potential evidence for dark matter detection.

Findings

Some sources match spectra of light (~5-40 GeV) dark matter particles.

Number of candidate sources aligns with predictions for dark matter subhalos.

Further multi-wavelength observations needed to confirm their nature.

Abstract

The dark matter halo of the Milky Way is expected to contain an abundance of smaller subhalos. These subhalos can be dense and produce potentially observable fluxes of gamma rays. In this paper, we search for dark matter subhalo candidates among the sources in the Fermi-LAT Second Source Catalog which are not currently identified or associated with counterparts at other wavelengths. Of the nine high-significance, high-latitude (|b|>60 degrees), non-variable, unidentified sources contained in this catalog, only one or two are compatible with the spectrum of a dark matter particle heavier than approximately 50-100 GeV. The majority of these nine sources, however, feature a spectrum that is compatible with that predicted from a lighter (~5-40 GeV) dark matter particle. This population is consistent with the number of observable subhalos predicted for a dark matter candidate in this mass range and with an annihilation cross section of a simple thermal relic (sigma v~3x10^{-26} cm^3/s). Observations in the direction of these sources at other wavelengths will be necessary to either reveal their astrophysical nature (as blazars or other active galactic nuclei, for example), or to further support the possibility that they are dark matter subhalos by failing to detect any non-gamma ray counterpart.